1. Field of the Invention
The invention relates to an apparatus for the admixing of a gaseous or vaporous substance, especially an odoriferous substance, into a gas stream in a mixing chamber, to which the gaseous or vaporous substance is fed by means of a carrier gas via a line.
2. Background Information
An apparatus for the mixing of odoriferous substances is taught in U.S. Pat. No. 4,520,651. In this apparatus, the vapors of the odoriferous substances are individually mixed with odorless carrier gas. These individual gas mixtures are then brought together in a mixing chamber in order to produce an odoriferous substance composition. The lines which lead the odorless gas to storage tanks containing the odoriferous substances have controllable valves: a shut off valve with which the odorless gas can be switched on and off and an adjusting valve with which the quantity of gas can be individually controlled.
This prior art apparatus has the disadvantage that when opening the valves, i.e., when switching in an individual odoriferous substance component or else when increasing the concentration in the lines, the surfaces first have to be saturated. The concentration of the odoriferous substance in the mixing chamber increases slowly until reaching a state of equilibrium. Conversely, during switching-out so-called memory effects occur, since odoriferous substances desorbing from the surfaces can get into the mixing chamber by diffusion. There is a relatively long waiting time until in each instance a state of equilibrium is reached and an assessment of the odor of the composition can be carried out.
A further disadvantage of the known mixing apparatus is that measurements of odor threshold values, at which precisely defined quantities of a gas saturated with odoriferous substance can be added to an odorless rarefaction gas, are not possible.